Effect of perfusionist technique on cerebral embolization during cardiopulmonary bypass

Abstract

Cerebral emboli associated with perfusionist interventions can be minimized by not purging the sampling manifold, using continuous infusions rather than bolus injections, and maintaining high blood-volume levels (>800mL) in the venous reservoir.

Cerebral Emboli Detected by Transcranial Doppler During Cardiopulmonary Bypass Are Not Correlated With Postoperative Cognitive Deficits

“…5,8,9,13 Some studies have found that patients undergoing CABG with higher HITS counts were more likely to experience cognitive deficits 1,2,5,6 or higher rates of frontal lobe dysfunction, 16 but others have found that there is no correlation between HITS counts and neurological symptoms or cognitive deficits. 6,8,17 Several methodological issues may account for the variability among these studies, including small sample sizes, 1,6 differences in intensity thresholds used to detect HITS, 13 artery location (carotid versus middle cerebral artery), 1,8,12 unilateral or bilateral recordings, 2,8,12 type of ultrasound device, 13,18 quality of TCD recordings, 18 inconsistency of signal reviewing techniques (automatic versus manual), 13,18 and the effects of several confounding variables such as the duration of CPB and core body temperature. 2 We sought to overcome these limitations by studying a large number of low-risk patients undergoing †HITS were recorded unilaterally in the left common carotid artery.…”

“…Our TCD equipment and reviewing procedures have been previously described. 12,13 Only embolic signals identified in the middle cerebral arteries with relative intensities Ͼ8 dB (intensity threshold) were accepted. Bilateral middle cerebral artery counts of HITS were grouped into periods that included the following surgical maneuvers: cannulation; defined from the time of aortic cannulation to before CPB initiation, CPB onset; from CPB initiation to immediately before the application of the aortic crossclamp, aortic X-clamp-on; from aortic crossclamping to immediately before declamping, aortic X-clamp-off; from aortic declamping to before aortic side-clamping, side clamp-on; from the application of the aortic side clamp to immediately before its release, side clamp-off; from aortic side clamp release to the end of CPB, and decannulation; from the time of CPB termination to immediately after aortic decannulation.…”

“…To determine differences associated with the technique of aortic clamping, we compared the sum of HITS from the time of the application of the aortic crossclamp to the end of CPB between single and dual-clamp techniques. The effects of perfusionist's interventions (ie, drug infusion, blood sampling) 12 on the HITS counts during the period of Aortic X-clamp-on were documented by the sum of all counts of HITS that occurred within the next minute after any perfusionist's intervention. Because perfusionist's interventions represent sources of air for cerebral emboli, 12 HITS associated with these interventions were excluded before determining the relationship between cerebral blood flow velocity and HITS counts.…”

Generation, Detection and Prevention of Gaseous Microemboli during Cardiopulmonary Bypass Procedure

“…Several in vitro studies have shown that various models of oxygenators and venous reservoirs differ with respect to both air bubble formation and venous air removal (24,25). Venous reservoirs with a long central snout that extends the venous inlet to the bottom of the reservoir near the outflow have limited capacity to remove GMe once air has been introduced into the venous line, particularly under conditions of low reservoir volume such as those occurring at the onset of cPB (7). In this type of circuit, air bubbles are less likely to float to the top of the reservoir and may be siphoned directly into the outflow.…”

Monodisperse bubbles and droplets for medical applications

“…The microbubbles originate mainly from interventions by the perfusionist, e.g. through air entrainment in a venous reservoir with a low volume level or through the administration of (drug-containing) liquids where the larger bubbles are fractionated into smaller GME by the different components of the CPB circuit 203 . GME are considered to contribute to the adverse outcome of cardiac surgery and they are associated with brain injury 204 as was statistically shown in several studies where transcranial Doppler ultrasound (TCD) imaging was used to measure GME loads in-vivo [205][206][207] .…”